ENGR00221970 MX6SL:Fix suspend/resume issue on MX6SLEVK

Make sure the Pull Ups are enabled on the DQS lines of
LPDDR2 memory. Without that its possible that the data
latched by the memory will be incorrect when exiting from
self-refresh mode. So only set the drive strengths to 0
when floating the DDR IO pads before entering suspend.

Also never float the CKE pad, this pin always needs to be
driven, else the DDR may incorrectly exit self-refresh.
Hence remove the line that was setting CKE drive strength
to zero (GRP_CTLDS).

Signed-off-by: Ranjani Vaidyanathan <ra5478@freescale.com>

diff --git a/arch/arm/mach-mx6/mx6_suspend.S b/arch/arm/mach-mx6/mx6_suspend.S
index 59b6760384273cd49a03271058ebd696bdcd5d65..a9b7e30cd85a81efe950721fe87ffa071ba8da55 100644 (file)
--- a/arch/arm/mach-mx6/mx6_suspend.S
+++ b/arch/arm/mach-mx6/mx6_suspend.S
@@ -85,8 +85,7 @@ r2: suspend_iram_base
        ldr     r4, [r1, #0x330] /* DRAM_SDCKE0 */
        ldr     r5, [r1, #0x334] /* DRAM_SDCKE1 */
        ldr     r6, [r1, #0x320] /* DRAM_RESET */
-       ldr     r7, [r1, #0x5c8] /* GPR_CTLDS */
-       stmfd   r0!, {r4-r7}
+       stmfd   r0!, {r4-r6}
 
        .endm
 
@@ -122,11 +121,10 @@ r2: suspend_iram_base
        str     r6, [r1, #0x33c] /* DRAM_SODT0*/
        str     r7, [r1, #0x340] /* DRAM_SODT1*/
 
-       ldmea   r0!, {r4-r7}
+       ldmea   r0!, {r4-r6}
        str     r4, [r1, #0x330] /* DRAM_SDCKE0 */
        str     r5, [r1, #0x334] /* DRAM_SDCKE1 */
        str     r6, [r1, #0x320] /* DRAM_RESET */
-       str     r7, [r1, #0x5c8] /* GPR_CTLDS */
 
        .endm
 
@@ -138,6 +136,13 @@ r2: suspend_iram_base
        str     r0, [r1, #0x314] /* DRAM_DQM2 */
        str     r0, [r1, #0x318] /* DRAM_DQM3 */
 
+       /* Make sure the Pull Ups are enabled.
+        * So only reduce the drive stength, but
+        * leave the pull-ups in the original state.
+        * This is required for LPDDR2.
+        */
+       ldr     r0, [r1, #0x344]
+       orr     r0, r0, #0x3000
        str     r0, [r1, #0x344] /* DRAM_SDQS0 */
        str     r0, [r1, #0x348] /* DRAM_SDQS1 */
        str     r0, [r1, #0x34c] /* DRAM_SDQS2 */
@@ -158,7 +163,6 @@ r2: suspend_iram_base
        str     r0, [r1, #0x33c] /* DRAM_SODT0*/
        str     r0, [r1, #0x340] /* DRAM_SODT1*/
 
-       str     r0, [r1, #0x5c8] /* GPR_CTLDS */
        mov     r0, #0x80000
        str     r0, [r1, #0x320] /* DRAM_RESET */
        mov     r0, #0x1000